The invention relates generally to communication systems and methods and more particularly to communication systems and methods that employ communication packet dropping to reduce communication link congestion.
Wireless internet protocol (IP) cellular networks are known which employ network elements, such as base transceiver stations which communicate wirelessly with wireless devices, such as PDAs, internet appliances, cellular telephones and other mobile and non-mobile devices. Such networks communicate packets of information to other network elements such as selection and distribution units (SDU's) which may then be connected to mobile switching centers and public switching telephone networks or packet data serving nodes, the Internet, or any other suitable element or network. The network elements, such as the base transceiver stations, which communicate wireless information to a wireless device, are typically coupled to other network elements via lower speed but heavily utilized communication links, sometimes referred to a backhaul links, such as T1 links or other suitable links. These backhaul links are then often connected to an access node that serves as a router which is then connected to an IP network such as a series of high speed links which are then coupled to other network elements.
Links which are very highly utilized, such as backhaul links, can become congested. This can serve as a bottleneck which can undesirably reduce the performance of a wireless device or of an entire network. For traffic in a reverse link communication, such as from the wireless device to the base transceiver station, queuing of packets for communication by the base transceiver station typically occurs at an output port of the base transceiver station that is coupled to the IP network. Alternatively, for forward link traffic, congestion typically occurs on the output port of the access node such as the router that is coupled with the base transceiver station via the backhaul link.
Routers are known in communication systems which drop packets based on IP packet header information. Such routers can use differing techniques for determining which packet to drop. For example, weighted random early detect (WRED) processes can be used to selectively drop packets that have different drop precedence values designated in the header portion of a packet. For example, routers may discard lower priority packets when the packets are located in a single queue based upon packet marking. Moreover, wireless communication systems are known to drop packets with unsuitable power levels or based on other criteria.
In digital cellular systems, it is common to send control/signaling information through the active traffic channel. Including control or signaling information in a traffic channel is commonly referred to as in-band signaling. The packets that carry this critical control/signaling information are mixed in with the router bearer traffic and transmitted in the packet network. Some examples of in-band signaling messages are handoff direction messages, indicating when and which handoff will occur between wireless devices, power control messages indicating the power level setting for a mobile device, extended handoff direction messages and other information, which is useful on a forward link communication.
In a reverse link, some critical in-band signaling message are the pilot strength measurement message, a power measurement report message indicating, for example, the amount of power detected in a signal, and a handoff completion message. However, not all packets on the traffic channel carry these critical signaling messages. In conventional communication systems, the critical signaling traffic is treated as bearer traffic on the backhaul link, and as such can experience the same delays as voice and bearer traffic rather than getting lower delays which are provided to out of band signaling traffic. Most of the in-band control signaling packets are real time signaling messages used for hand off and power control. The fast delivery of these messages can be crucial in order to provide adequate quality of service to end users. Moreover, certain information is more critical than other information. For example, it may be more desirable to ensure that voice frames are not dropped during a communication and instead other types of packets with less impact on quality of service could be dropped to reduce congestion in a backhaul link.
Accordingly, a need exists for an approved method and apparatus for enhancing the quality of service of a wireless communication.